An enantioselective synthesis of α-alkylated pyrroles <i>via</i> cooperative isothiourea/palladium catalysis

Scaggs, William R.; Scaggs, Toya D.; Snaddon, Thomas N.

doi:10.1039/c8ob02600a

Cited by 34 publications

(9 citation statements)

References 44 publications

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“… 403 Pyrrolyl-acetic esters were also α-allylated with a range of allyl sulfonates or carbonates with high levels of enantioselectivity ( Scheme 125 b). 404 This allylation method was also combined with a subsequent Hofmann rearrangement in a one-pot procedure. In this way, carbamate-protected branched homoallylic amines were prepared with high enantioselectivity ( Scheme 125 c).…”

Section: Asymmetric Allylic Substitutionmentioning

confidence: 99%

Recent Advances in Enantioselective Pd-Catalyzed Allylic Substitution: From Design to Applications

Pàmies

Margalef

Cañellas³

et al. 2021

Chem. Rev.

371

202

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This Review compiles the evolution, mechanistic understanding, and more recent advances in enantioselective Pd-catalyzed allylic substitution and decarboxylative and oxidative allylic substitutions. For each reaction, the catalytic data, as well as examples of their application to the synthesis of more complex molecules, are collected. Sections in which we discuss key mechanistic aspects for high selectivity and a comparison with other metals (with advantages and disadvantages) are also included. For Pd-catalyzed asymmetric allylic substitution, the catalytic data are grouped according to the type of nucleophile employed. Because of the prominent position of the use of stabilized carbon nucleophiles and heteronucleophiles, many chiral ligands have been developed. To better compare the results, they are presented grouped by ligand types. Pd-catalyzed asymmetric decarboxylative reactions are mainly promoted by PHOX or Trost ligands, which justifies organizing this section in chronological order. For asymmetric oxidative allylic substitution the results are grouped according to the type of nucleophile used.

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Section: Asymmetric Allylic Substitutionmentioning

confidence: 99%

Recent Advances in Enantioselective Pd-Catalyzed Allylic Substitution: From Design to Applications

Pàmies

Margalef

Cañellas³

et al. 2021

Chem. Rev.

371

202

View full text Add to dashboard Cite

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“…A very efficient strategy for the asymmetric intermolecular allylic alkylation of pyrroles under cooperative catalysis was developed by Snaddon and his group in 2018 (Scheme 40). [107] Using 20 mol% of Birman's benzotetramisole C-30 and 5 mol% of Buchwald's 3 rd generation Xantphos-ligated Pd pre-catalyst C-31, the desired α-functionalized pyrrole-acetic acid ester products 109, bearing tertiary stereogenic centers has been achieved in moderate to good yield with excellent enantioselectivity. This cooperative catalytic condition was found to be compatible for a variety of N-substituted pyrroles 107 as the nucleophiles and substituted allyl group 108 as the electrophiles.…”

Section: Asymmetric Allylic Substitution Reactionmentioning

confidence: 99%

Recent Advances in Metal‐ and Organocatalyzed Asymmetric Functionalization of Pyrroles

2021

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The wide occurrence of pyrroles in natural products and pharmaceuticals calls for novel synthetic methodologies for the efficient synthesis of enantiopure pyrroles. Owing to their highly reactive nature and wide-ranging chemical landscape, enormous efforts have been dedicated not only to their synthesis but also to the development of reactions using them as a platform and their utilization in the stereocontrolled synthesis of diverse molecules. In sharp contrast to the extensive studies devoted toward indoles, the asymmetric functionalization of pyrroles was less explored. Never-theless, the attractiveness of pyrroles for their selective functionalization to access natural product analogy, and medicinally useful architectures have witnessed tremendous growth in the last few years. Their effectiveness under both metal-and organocatalytic conditions currently encompasses a vast majority of enantioselective transformations. This review article aims to present a comprehensive overview of the catalytic asymmetric CÀ H as well as NÀ H functionalization of pyrroles reported from 2010 to now.

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“…Snaddon and co‐workers have also broadened the scope of the nucleophile component in the dual catalysed allylation protocol to pyrrole 2‐acetic acid pentafluorophenyl esters 149 , enabling the enantioselective synthesis of α‐alkylated pyrroles 151 (Scheme 33). [79] N ‐Alkyl, benzyl and allyl substituted pyrroles were tolerated, giving the corresponding allylated products in high yields with excellent enantioselectivity. Notably, no undesired allylation of the electron rich pyrrole ring was observed.…”

Section: Catalyst Turnover Via Aryloxidementioning

confidence: 99%

Generation and Reactivity of C(1)‐Ammonium Enolates by Using Isothiourea Catalysis

McLaughlin

Smith

2020

Chemistry A European J

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C(1)‐Ammonium enolates are powerful, catalytically generated synthetic intermediates applied in the enantioselective α‐functionalisation of carboxylic acid derivatives. This minireview describes the recent developments in the generation and application of C(1)‐ammonium enolates from various precursors (carboxylic acids, anhydrides, acyl imidazoles, aryl esters, α‐diazoketones, alkyl halides) using isothiourea Lewis base organocatalysts. Their synthetic utility in intra‐ and intermolecular enantioselective C−C and C−X bond forming processes on reaction with various electrophiles will be showcased utilising two distinct catalyst turnover approaches.

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An enantioselective synthesis of α-alkylated pyrroles via cooperative isothiourea/palladium catalysis

Abstract: Herein we describe the direct enantioselective Lewis base/Pd catalysed α-allylation of pyrrole acetic acid esters.

Cited by 34 publications

References 44 publications

Recent Advances in Enantioselective Pd-Catalyzed Allylic Substitution: From Design to Applications

Recent Advances in Enantioselective Pd-Catalyzed Allylic Substitution: From Design to Applications

Recent Advances in Metal‐ and Organocatalyzed Asymmetric Functionalization of Pyrroles

Generation and Reactivity of C(1)‐Ammonium Enolates by Using Isothiourea Catalysis

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